A load balancer written in .NET
It can use four load balancing algorithms:
- Round Robin
- Weighted Round Robin
- Least Connections
- Sticky Sessions
The algorithm to be used is defined in the Libra node of the appsettings.json file.
This is the simplest algorithm used by Libra.NET. It schedules in an equal manner the usage of the Servers configured.
This is a little bit complex. Weighted Round Robin is a more advanced load balancing configuration. This technique allows you to point records to multiple IP addresses like basic Round Robin, but has the added flexibility of distributing weight based on the needs of your domain. Every server configured has a weight that is assigned by Libra.NET using the position in the array. If a server is in an higher position in the list the weight applied increase.
This is not so complex. Least connections load balancing is a dynamic load balancing algorithm where client requests are distributed to the application server with the least number of active connections at the time the client request is received.
This is not so complex. Sticky sessions load balancing is a dynamic load balancing algorithm where client requests are sent only to one client for session id provided.
Add this section to appsettings.json.
"LibraNet": {
"LoadBalancingPolicy": "RoundRobin",
"Servers": [
"10.0.0.0",
"10.255.255.255",
"https://10.0.0.1:443",
"my-in-balancer-server.xyz",
"https://my-in-balancer-server2.xyz:443"
]
}
The configuration is made of:
| Property | Type | Context | Allowed Values |
|---|---|---|---|
| LoadBalancingPolicy | string | The value of the load balancing algorithm to apply. | RoundRobin, WeightedRoundRobin, LeastConnections |
| Servers | array | The list of servers that are under load balancing. | A valid ipaddress (with or without port) or an hostname |
Libra.NET exposes one extension:
AddLibraNet(this IHostBuilder builder);
This extension it is used for:
- Registering of LoadBalancingConfiguration from appsettings.json by environment.
- Registering of ILoadBalancingAlgorithm implementations.
- Registering of HttpRequestManager implementation.
It must be used to use Libra.NET
This component exposes one method:
public async Task ForwardRequest(HttpContext context, Server? destinationServer, CancellationToken cancellationToken = default)
that given an HttpContext and a Server as destination forwards to it the call, waits for the response and copies it in the HttpContext.Response.
To use in a simple way Libra.NET there is a middleware, called LoadBalancingMiddleware. It is an ASP.NET middleware that, using the LoadBalancingConfiguration.LoadBalancingPolicy, retrieves the correct algorithm to find the destination server with the LoadBalancingAlgorithmFactory and uses the HttpRequestManager to forward the request.